Bonding magnesium-alloy sheets



Jan. 2, 1945. R w, BAKARIAN 2,366,168

BONDING MAGNESIUM-ALQOY SHEET Filed May 2, 1942 Sprayed coa f/ng of fed; 2 or 04-21 al/oy 1 My base alloy .sheef My base a/loy sheaf Sprayed coafing My base alloy .sbeef Fig. 2

M9 base allay .s/Ieef Coa f/ng H K S Tack 'we/a' Mg base alloy sheaf IN V EN TOR; Puz anl- MA Bakarian ATTORNEYS 2,368,168 o BONDING MAGNESIUMQQLLOY SHEETS, Y Puzant -W. Bakarlan, Midland; Migh Maui! Company; Midland, Mich, acorporatlonofMichigan. r

Application May 2, 1942, Serial No. 441,531 j v3 Claims. (01'. 29' 189)' ,7 a This invention relates to animproved method Figiais an enlarged view show-r of bonding together magnesium-base alloy sheets. ing ,theisheets of Fig; 2 brought together and Composite articles consisting of sheets-of two tack-welded at the-Bidet 1 or mor different magnesium-base alloys united 5t is'i'a cross secfionalview of the sheets J; by a firm bond are desirable'ior a variety of. 5 of'Flg. 3 being reduoedinsthickness by'r01 in8; structural purposes. In particular, sheets obnforming'a' bonded'pair ofmagnesiurn alloy sheetsr sisting of a core metal Iormed'of an alloy charo alloy sheem are acterized by extreme strength clad with a thin first'carefulls'r cl' layer of an alloy of the highly corrosion resistganic matter, ant type are especially useful in that :such .com- "10 may h pre posite sheets exhibit a'combination or the desire 3 able properties of both alloys without'thedisadvantages of either. A number ot methods'oi forming such composite'sheets are known, but a l non provides a bond between thetwo sheets m-coating'wof meta possible'asshowniin which is strong enough to withstand without r'up- V the sprayingmeansbeing adjusted and opera ture the severe stresses to which th sheet :is v ftoprovidea film sometimes subjected during fabrication and usel An object of the present; invention, then, is; to provide an improved methodof making composite articles formed of two or more different; magnesium-base alloys inwhichfthe individual alloy sheets forming the-article. areheld together by a firm strong bond cap'able'oi resisting a1 stresses to which such" articles, are ordinarily: subjected. 1 I In the. process of the invention atQleast on M of each two magnesium alloy. sheets to be bonded gas-such as. the Metco A tallizing together is sprayed witha moltenmetal, speciflough' otherspray devioes'may cally zinc, cadmium, or alloys vthereoftvith a. 'minor proportion of magnesium, to -iorm' a film of solid'me'tallon thesheet. be bonded ar thensuperim other withthe spray'ed film' at -th are heatedito a temperature ab but below the. melting point of:

vDfl-nying' this rolling appear to'causefdifl the two adjacent magnesium-base it and thustoform astrong bond'betwj n theptwo molten bonding metal. reduction in thicknessof the pack per pass are then passed toeeth "tape more times between rolls adjusted y 91; rateoivreduction in thickness of jt o I M sheetl per pass of :at'least'l l) per cent. r eration of heat-and mechanical workin acco the zinc or cadmium: of the nfer-moi sheets. a

In the drawingi V 3 f e Following the heating.thepack of sheetsQwhHe Fig. 1 is an enlarged cross-sectional view of a still hot, is passed one or more times through a magnesium-base alloy. sheet spray coated with conventional rolling mill adjusted to produces;

Fig. 2 is an enlarged cross-sectional I view of through the rolls, as shown in Fig. 4, of at'least superimposed magnesium-base alloy sheets, one about 10 per cent; reductions of 15 per cent or hav n & pray oa of molten bonding more per pass are preferred, the maximum rate metal. i a 7 5s beingabout per cent. Atter'the rolllng stemfi The composite article thus formed may then be subjected'to further rolling and annealing operations desired to develop any range on. physical characteristics, of which the metal is capable, and may be cut, punched, drawn, or otherwise shaped without danger of rupturing the bond between the original sheets.

In so' far as is known, the process of the invention may satisfactorily be applied to bonding together sheets formed of any two different magnesium-base alloys. As a practical matter, however, the invention finds its greatest application in cladding high strength magnesium-base alloys containing aluminum in a quantity up to per cent as the major alloying element with highly corrosion resistant alloys containing manganese in a quantity up to 2 per cent as the major alloying element. In this way there is formed a composite article having a high strength core and surfaces of high corrosion resistance.

The following example will further illustrate the invention, but is not to be construed as limiting the scope:

Example A 0.5 x 4 x 8 (inch extruded slab of Dowmetal J (a magnesium-base alloy containing 6.5 per cent aluminum, 0.2 per cent manganese, and 0.7 per cent zinc, the balance being magnesium) was carefully cleaned and sandblasted and was sprayed on both sides with molten zinc to form a uniform skin of zinc 0.0005 inch thick upon each side. Similarly sized sheets of Dowmetal M (a magnesium-base alloy containing 1.5 per cent manganese, the balance being magnesium) 0.030 inch thick were then placed on each side of the sprayed sheet to form a packet, and the latter was wired securely. The packet was then introduced into a heat-treating oven and heated for one hour at a'temperature of 700 F., after which it was withdrawn from the oven and passed twice through a conventional rolling mill adjusted to produce a total reduction in thickness of per cent on each pass. The sheet was then reheated to a temperature of 700 F. and again passed repeatedly through the mill at a reduction of 15 per cent per pass until a total thickness of 0.090 inch was reached. The resulting sheet exhibited a firm strong bond between the individual sheet elements.

Other modes of apply g the principle of the invention may be employed instead of those explained, change being made as regards the details described, provided the steps recited in any of the followin claims or the equivalent thereof-be 6 used.

I claim:

1. The method of bonding together sheets formed of different magnesium-base alloys which comprises: spray g a molten metal selected from 10 the class consisting of zinc, cadmium, and alloys thereof with a minor proportion of magnesium upon a surface of at least one of the sheets to be bonded to form thereon a film of solid metal having a thickness between about 0.0005 and 15 about 0.005 inch; superimposing the sheets one upon the other with the metal coating at the interface; heating the sheets to a temperature above about 600 F. but below the melting point,

of the metal forming the coating while holding the sheets together; and passing the superimposed heated sheets together through rolls at a rate of reduction in thickness per pass between about 10 and about 60 per cent.

2. The method of bonding together sheets formed of difierent magnesium-base alloys which @comprises: spraying molten zinc on the surface of at least one of the sheets to be bonded to form thereon a film of solid zinc having a thickness between about 0.0005 and about 0.002 inch; superimposing the sheets one upon the other with the zinc coating at the interface; heating the sheets to atemperature between about 6'15 and about 725 F. while holding the sheets together; and passing the superimposed heated sheets together through rolls at a rate of reduction in thickness per pass between about 15 and about 60 per cent. 3. The method of bonding a sheet formed of a magnesium-bas alloy containing manganese in a, quantity up to 2 per cent by weight as the major alloying element to a sheet formed of a 'magnesium-base alloycontainingaluminum in aquantityup to 10 per cent as the major alloying element which comprises; spraying molten zinc on the surface of at least one of the sheets to form thereon a film of solid zinc about 0.0005 to 0.002 inch thick; superimposing the sheets one upon the other with the zinc coating at the interface; heating the sheet to a temperature of about 690 F. while holding the sheets together; and passing the su- D rimposed sheet together through rolls at a rate of reduction in thickness per pass of about 15 per cent.

PUZANT W. BAKARIAN. 

